High efficiency, wet-base, downfired multi-pass water heater

Abstract

A fuel-fired water heater has a three-pass condensing type heat exchanger disposed within its tank and having a central vertical first pass flue pipe separated into upper and lower portions by an internal dividing structure. Respectively coupled to the upper and lower first pass flue pipe portions are circumferentially spaced series of vertical second and third pass flue pipes which circumscribe the central flue pipe within the tank. During firing of the water heater, combustion gases from a power burner are sequentially forced downwardly through the upper portion of the first pass flue pipe, upwardly through the second pass flue pipes to an upper plenum external to the tank, and then downwardly through the third pass flue pipes and the lower central pipe portion into a bottom plenum external to the tank for discharge from the water heater.

Description

BACKGROUND OF THE INVENTION[0001]The present invention generally relates to fuel-fired fluid heating devices and, in a representatively illustrated embodiment thereof, more particularly provides a fuel-fired water heater having a specially designed multi-pass condensing type heat exchanger incorporated therein.[0002]Conventional fuel-fired water heaters are typically of a “single pass”, non-condensing configuration, meaning that the hot combustion gases used to heat the tank-stored water are subjected to only a single pass through a heat exchanger structure (usually a vertical flue) within the tank before being discharged from the water heater to, for example, an external vent structure, and that flue gas condensation does not occur to any appreciable degree in the heat exchanger structure within the water heater tank. In this conventional type of fuel-fired water heater, the overall thermal efficiency is typically limited to about 80-85%. Various proposals have been made to provide...

AI Technical Summary

Benefits of technology

The three-pass heat exchanger achieves thermal efficiency of 95% or above, reduces fabrication and operational complexity, and allows for easier condensate management, while maintaining a robust and efficient heating system.

Problems solved by technology

In this conventional type of fuel-fired water heater, the overall thermal efficiency is typically limited to about 80-85%.

However, previously proposed single-pass condensing type heat exchange structures incorporated in fuel-fired water heaters typically provide the water heaters with thermal efficiencies limited to the 85-90% range.

While such previously proposed multi-pass condensing type heat exchangers have met this thermal efficiency goal, they have also undesirably presented various problems, limitations and disadvantages.

These include increased heat exchanger complexity, higher material and fabricational costs, condensate management problems, increased operational noise, and reduced heat exchanger operational life.

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